A can do a piece of work in 10 days and B can do it in 12 days. They work together for 2 days, then B leaves and A alone continues. 3 days later C joins and the work is completed in 2 more days. In how many days can C do the work alone?
Answer & explanation
Correct answer: option 1
Work done by A and B together in 2 days = efficiency x no. of days = 11 x 2 = 22
Work left after this = 60 - 22 = 38
This work is continues by A alone in the next 3 days,
With efficiency of 6, work done by A = 6 x 3 = 18
Work lefty thereafter, 38 - 18 = 20
This is completed by A and C in 2 days,
then efficiency of A and C together = \(\frac{work}{no.\; of\;\; days}\)
=\(\frac{20}{2}\) = 10
Efficiency of C = 10 - 6 = 4
Time taken C alone to do the total work = \(\frac{Total\; work }{efficiency}\)
= \(\frac{60}{4}\) = 15 days